String: Add support for __memcmpeq() ABI on all targets

No bug.

This commit adds support for __memcmpeq() as a new ABI for all
targets. In this commit __memcmpeq() is implemented only as an alias
to the corresponding targets memcmp() implementation. __memcmpeq() is
added as a new symbol starting with GLIBC_2.35 and defined in string.h
with comments explaining its behavior. Basic tests that it is callable
and works where added in string/tester.c

As discussed in the proposal "Add new ABI '__memcmpeq()' to libc"
__memcmpeq() is essentially a reserved namespace for bcmp(). The means
is shares the same specifications as memcmp() except the return value
for non-equal byte sequences is any non-zero value. This is less
strict than memcmp()'s return value specification and can be better
optimized when a boolean return is all that is needed.

__memcmpeq() is meant to only be called by compilers if they can prove
that the return value of a memcmp() call is only used for its boolean
value.

All tests in string/tester.c passed. As well build succeeds on
x86_64-linux-gnu target.

5 files changed, 10 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc32/405/memcmp.S b/sysdeps/powerpc/powerpc32/405/memcmp.S
index 6a6a54d90f..c2836040a7 100644
--- a/sysdeps/powerpc/powerpc32/405/memcmp.S
+++ b/sysdeps/powerpc/powerpc32/405/memcmp.S
@@ -126,3 +126,4 @@ L(st2):
 END (memcmp)
 libc_hidden_builtin_def (memcmp)
 weak_alias (memcmp,bcmp)
+strong_alias (memcmp, __memcmpeq)
diff --git a/sysdeps/powerpc/powerpc32/power4/memcmp.S b/sysdeps/powerpc/powerpc32/power4/memcmp.S
index 814d2f211d..f58e34aba5 100644
--- a/sysdeps/powerpc/powerpc32/power4/memcmp.S
+++ b/sysdeps/powerpc/powerpc32/power4/memcmp.S
@@ -1373,3 +1373,4 @@ END (memcmp)
 
 libc_hidden_builtin_def (memcmp)
 weak_alias (memcmp, bcmp)
+strong_alias (memcmp, __memcmpeq)
diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-power7.S b/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-power7.S
index 8a929b2b44..b17d0e43b7 100644
--- a/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-power7.S
+++ b/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-power7.S
@@ -38,4 +38,7 @@
 #undef weak_alias
 #define weak_alias(a, b)
 
+#undef strong_alias
+#define strong_alias(a, b)
+
 #include <sysdeps/powerpc/powerpc32/power7/memcmp.S>
diff --git a/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-ppc32.S b/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-ppc32.S
index 317523b743..893b6cac9c 100644
--- a/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-ppc32.S
+++ b/sysdeps/powerpc/powerpc32/power4/multiarch/memcmp-ppc32.S
@@ -40,6 +40,10 @@
 # undef weak_alias
 # define weak_alias(a, b)					\
   .weak b ; b = __memcmp_ppc
+
+# undef strong_alias
+# define strong_alias(a, b)					\
+  .globl b ; b = __memcmp_ppc
 #endif
 
 #include <sysdeps/powerpc/powerpc32/power4/memcmp.S>
diff --git a/sysdeps/powerpc/powerpc32/power7/memcmp.S b/sysdeps/powerpc/powerpc32/power7/memcmp.S
index 8a19953e2d..f8deb4e32c 100644
--- a/sysdeps/powerpc/powerpc32/power7/memcmp.S
+++ b/sysdeps/powerpc/powerpc32/power7/memcmp.S
@@ -1373,3 +1373,4 @@ END (memcmp)
 
 libc_hidden_builtin_def (memcmp)
 weak_alias (memcmp, bcmp)
+strong_alias (memcmp, __memcmpeq)